<!DOCTYPE html>
<html lang = "en">
<head>
  <meta charset = "UTF-8">
  <title>Title</title>
  <!--MD5加密工具类-->
  <script src = "https://cdn.bootcss.com/blueimp-md5/2.10.0/js/md5.min.js">

  </script>
</head>
<body>
<!--表达绑定提交事件
    οnsubmit= 绑定一个提交检测的函数，true，false
    将这个结果返回给表单，使用onsubmit接收
-->
<form action = "https://www.baidu.com" method = "post" onsubmit = "return check()">
  <p>
    <span>用户名：</span><input type="text" id = "username" name = "username"/>
  </p>
  <p>
    <span>密码：</span><input type="password" id = "password" />
  </p>
  <input type = "hidden" id = "md5-password" name = "password">

  <!--绑定事件 onclick 被点击-->
  <button type = "submit">提交</button>

</form>

<script>
  function check(){
    alert(1);
    var username = document.getElementById("username");
    var pwd = document.getElementById("password");
    var md5pwd = document.getElementById("md5-password");
    //MD5算法
    //pwd.value = md5(pwd,value);
    md5pwd.value = md5(pwd.value);
    //可以校验判断表单内容，true就是通过提交，false就是阻止提交
    return true;

  }
</script>

</body>
</html>
